The present project is designed to analyze the behavioral and neurophysiological aspects of two types of behavioral alterations seen in spinal reflexes. The first of these is the change in spinal response amplitude which has been shown to reliably occur when the cat flexion reflex is exposed to a classical conditioning paradigm. Studies performed under this project have delineated the interstimulus interval function of the conditioning effect, the retention characteristics and other features, and work is currently underway to determine the areas of the reflex arc involved in the alteration. The present analysis of the effects of a classical conditioning paradigm on the flexion reflex suggest a close correlation with classical conditioning in the intact organism. The second alteration is known as spinal fixation. Basically, it has been found that a variety of lesions of the CNS will produce certain postural alterations in a decerebrate or anesthetized animal. If a spinal transection is performed after 45 minutes of continuous alteration, this alteration remains in the limbs below the transection. The study is aimed at an analysis of this spinal "memory" in the reflex pathways. BIBLIOGRAPHIC REFERENCES: Cassady, M., Patterson, M.M. and Roemer, R. The use of on-line computers in psychobiology. Behavior Research Methods and Instrumentation, 1976, 8(2), 153-156. Cegavske, C.F., Thompson, R.F., Patterson, M.M. and Gormezano, I. Mechanisms of efferent $ neuronal control of the reflex nictitating membrane response in rabbit (Oryctolagus cuniculus). Journal of Comparative and Physiological Psychology, 90(5), 1976.